2K R/T surging

[Ted 00 R/T]

HI all. I need some help here. I have a 2k D R/T. with 50K miles. Today on a road trip cruising down the freeway at 60+ it started to surge. It would increase in rpm about 200 RPM then back down. I long as I had my foot in it was just fine. But just normal cruising it would jump up then come down surge up then down. Any ideas.

[BlueCC00RT]

I had the same problem with my 2k also it would surge while stopped (few and far inbetween) I removed my TB and cleaned all parts hasnt done it since

[Blowndakrt]

I would say your TPS Sensor is going bad. That is one of the symptoms of it. Mainly does it while cruising at a constant speed, with cruise on, or holding your foot steady. The jump in RPMS is actually your torque converter coming in and out of lock up.

A way to check it is to drive down the highway, and without moving your foot off the gas, just lightly touch the brake pedal. Just enough to activate the brake lights. That will cause your torque converter to come out of lockup, and it will jump a few hundred rpms. If the rpms fluctuation is the same as the problems you are describing, then it is more than likely the TPS sensor.

Hope that helps

Shawn

[2Evil4U]

I just noticed our '01 Durango does the same thing in cruise at 65 or so. I figured it was the torque convertor flipping between open and lock. Why does the Throttle Position Sensor affect the lockup of the torque convertor? Anybody know the actuation logic for the lockup function? I'm going to check the voltage output sweep on the TPS and see if it's erratic at all.

Thanks!

Update: I checked the output of the TPS and it is smooth as silk from 0.6V closed through 3.7V at WOT. Is that the correct voltage range for these vehicles?

[Blowndakrt]

I am not sure of why that affects the converter. I would guess that it has to to with engine load, and calculates throttle position to determine down shifts, up shifts, and lockup.

That voltage seems little low for WOT. Should be closer to 4.5 Volts at WOT.



Hope that helps

Shawn

[2Evil4U]

Thanks for the info. I took it apart and cleaned it out good last week. Now if my wife ever lets me drive it I can see if it's still screwing up. :)

[Blowndakrt]

No Prob. Hope it works out for ya.


Shawn

[2Evil4U]

Well, I put a new TPS in and it is perfect. The truck shifts much more consistantly and stays in lockup until you really get on it. I'm surprised though, that the voltage output of the new sensor is not much different than the old one. The new sensor puts out from 0.6V through about 3.8V. But, that's not important I guess, since the tranny is acting properly.

Thanks!

[Blowndakrt]

Well I think the lockup is more controlled with the numbers in between. So if it had the slightless change in the area where you cruise at, then it would not know what to do.

I can't really explain why it does that. Don't know for sure. Glad yours was the problem. I hate giving people bad advice, so I can only go by stuff I have experienced.



Shawn

[autob79]

Hello, I have the same surge symptom as described above. I have tried changing the TPS two times now, and it only helped for a short while. (maybe a few days) I bought one from the dealer, and one from carquest. Anyone have any other ideas as to what the problem may be? I can't believe that this surging is good for the transmission. Please help.
Thanks for your time,
Autob79

[Blowndakrt]

autob79, Not sure what would cause the TPS's to go bad. How long does it take for the problem to come back?

It could be the actual TCC sensor is faulty also. Now that I think of it, I don't think it is actually called the TCC sensor, but don't have my book in front of me. But it could be the actual lockup solenoid. Sorry can't think of the name of that sensor.

How many miles are one the truck? What year is it? I know when mine first acted up, I took it in under warranty. They thought that the front pump was acting up, causing pulses in the pressure. So that might be another possiblity too.


Shawn